Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

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Resolving dependencies...
Starting     libltdl-0.1.1.2
Building     libltdl-0.1.1.2
Failed to install libltdl-0.1.1.2
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/libltdl-0.1.1.2-4rZ0zGdYhut6LDjPVkDJC8.log ):
cabal: Entering directory '/tmp/cabal-tmp-556/libltdl-0.1.1.2'
Configuring libltdl-0.1.1.2...
checking for gcc... /usr/bin/gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables... 
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether /usr/bin/gcc accepts -g... yes
checking for /usr/bin/gcc option to accept ISO C89... none needed
checking how to run the C preprocessor... /usr/bin/gcc -E
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for ltdl library... checking ltdl.h usability... no
checking ltdl.h presence... no
checking for ltdl.h... no
checking for lt_dlinit in -lltdl... no
configure: creating ./config.status
config.status: creating libltdl.buildinfo
Preprocessing library for libltdl-0.1.1.2..
Internal.hsc:39:10: fatal error: ltdl.h: No such file or directory
compilation terminated.
compiling dist/build/Foreign/LibLTDL/Internal_hsc_make.c failed (exit code 1)
command was: /usr/bin/gcc -c dist/build/Foreign/LibLTDL/Internal_hsc_make.c -o dist/build/Foreign/LibLTDL/Internal_hsc_make.o -fno-stack-protector -fno-stack-protector -fuse-ld=gold -D__GLASGOW_HASKELL__=806 -Dlinux_BUILD_OS=1 -Dx86_64_BUILD_ARCH=1 -Dlinux_HOST_OS=1 -Dx86_64_HOST_ARCH=1 -Idist/build/autogen -Idist/build/global-autogen -include dist/build/autogen/cabal_macros.h -I/opt/ghc/8.6.3/lib/ghc-8.6.3/base-4.12.0.0/include -I/opt/ghc/8.6.3/lib/ghc-8.6.3/integer-gmp-1.0.2.0/include -I/opt/ghc/8.6.3/lib/ghc-8.6.3/include -I/opt/ghc/8.6.3/lib/ghc-8.6.3/include/
cabal: Leaving directory '/tmp/cabal-tmp-556/libltdl-0.1.1.2'
cabal: Error: some packages failed to install:
libltdl-0.1.1.2-4rZ0zGdYhut6LDjPVkDJC8 failed during the building phase. The
exception was:
ExitFailure 1